1. Field of the Invention
The present invention relates to an ink for an inkjet, a processing liquid for inkjet, an ink set for an inkjet, an ink tank for an inkjet, an inkjet recording method, and an inkjet recording apparatus.
2. Description of the Related Art
Inkjet systems for ejecting ink from an ink ejection port formed of a nozzle, a slit or a porous film have been used in many printers due to their being small-sized and inexpensive. Of these inkjet systems, a piezo inkjet system for ejecting ink by utilizing the deformation of a piezoelectric element and a thermal inkjet system for ejecting ink by utilizing the boiling phenomenon of an ink by applying thermal energy are excellent in a high resolution and a high-speed printing property.
According to the inkjet system, a method of improving the image quality by preventing blurring by ejecting a processing liquid having a function of aggregating or insolubilizing a colorant, or the like as an ink component such that the liquid is brought into contact with the ink on a recording medium has been discussed.
By aggregating or insolubilzing the ink component, a high image quality can be obtained owing to the presence of the colorant at a high density in the vicinity of the surface of the recording medium, however, on the other hand, a problem that the reliability such as the rub resistance becomes poor arises.
In order to improve the problem, a method of adding a polymer into an ink to aggregate or insolubilize the polymer together with a pigment has been known as a method of improving the rub resistance of an image.
For example, Japanese Patent Application Laid-Open (JP-A) No. 2000-212486 discloses an ink containing 0.1 to 1 part by weight of a styrene-(meth)acrylic acid-based water-soluble resin as a pigment dispersing agent. Further, JP-A No. 2004-122465 discloses a method of forming a covering layer on at least a part of an image, using an ink containing a pigment and a polymer having —COOA by 10 to 100% with respect to the weight of the pigment. Moreover, JP-A No. 8-25801 discloses those in which one of polyvinyl pyrrolidone and polyacrylic acid is contained, which are different from each other in a liquid composition and an ink, respectively.
However, since the polymers to be added in accordance with these proposals are linear polymers, although the rub resistance can be obtained, it is not sufficient from the viewpoint of the recent high technical demand, and thus the improvement is desired in the present situation.